1. Field of the Invention
The present invention is directed to a frequency-controlled heart pacemaker, and in particular to a heart pacemaker wherein the stimulation frequency is controlled dependent on a measurement of the blood oxygen saturation of the patient.
2. Description of the Prior Art
Controlling the stimulation frequency of a heart pacemaker based on a measurement of the blood oxygen saturation of the patient is known, for example, from German OS No. 34 22 913.
It is also known that as the body enters into the anaerobic metabolic condition given higher stress, changes in the blood oxygen saturation asymptotically approach a zero value. This can cause conventional pacemaker control systems, making use of blood oxygen saturation as a factor in setting the stimulation frequency, to operate imprecisely when the body is in a higher stress condition.